Wireless Sensor Networks (WSNs) are deployed in hostile environments in many applications. In a wireless sensor networks, such regular topology patterns as square, hexagonal and triangle can fully cover the area, provides accurate positioning for abnormal event and achieve better network performance than random topology. In order to resist security threats, sensor nodes of WSNs often use pre-shared secret keys to encrypt and exchange confidential data. Accordingly, designing key management protocols that can securely distribute secret keys among sensor nodes becomes an important issue for WSNs. The proposed scheme analyses a novel key management protocol for hierarchical WSNs based on hexagonal topology using tree.